The present invention relates to a payload projectile, and more particularly to a payload projectile which includes a carrier for an ejectable payload, such as explosive secondary ammunition.
In one type of such a payload projectile, a supporting carrier body has an ogival region provided with a circularly cylindrical or frustoconical chamber for an ejection charge, an axially centrally perforated disc and a chamber for an igniter for actuating the ejection charge, the tip of the supporting body being closed by a lifting ring screw which includes a melting fuse and is sealed by a gasket fixed by the screw. Immediately in front of the ejection charge is a seat for seating the disc. The chamber for the igniter is in the ogival region just forward of the disc. This chamber is defined at its front and rear by the frontal face of the disc and the rear face of the lifting screw, respectively. The rear face of the lifting screw has a passage containing a melting fuse. To be noted is that during storage of the payload projectile at an ammunition depot or during transport, the chamber for the igniter is normally empty for reasons of safety to be explained below.
In a prior payload projectile of this type, the outer surface of the seat for the disc and the peripheral surface of the carrier body immediately forward of the seat which surrounds the chamber for the igniter, have the same radial dimensions, while the rear face of the lifting ring screw is planar. For reasons of safety, no igniter is disposed in the space provided for it, prior to reaching its location of use. To equip the payload projectile with the igniter at its location of use, the lifting ring screw is initially unscrewed, the igniter is inserted and then the lifting ring screw is screwed in again. When the igniter is in place, the disc between igniter and ejection charge serves to protect the igniter; a central bore in the disc, on the one hand, forms an ignition channel for actuating the ejection charge and, on the other hand, protects the igniter during pressure build-up so that the developed pressure is available substantially completely for the ejection process.
While a melting fuse disposed in a passage of the lifting ring screw responds by melting at a temperature of about 95.degree. C., the ignition temperature for the ejection charge lies in a range around 130.degree. C. Nevertheless, in the case of fire or intense solar radiation, inadvertent ejection has occurred in such a prior payload projectile in spite of the absence of the igniter, and the fuse being actuated in time. This has happened because the disc had moved against the planar rear face of the lifting ring screw and the passage cross section of the ignition channel was not sufficient to prevent a buildup of damaging internal pressure.